"Both the officials and the player involved in the unsportsmanlike conduct penalty were not confused as to why a flag was thrown. The player was flagged, correctly, for the slide on his knees in the end zone, not for going to the ground in a prayerful gesture," said retired referee and former NFLRA president Scott Green in the release. "On field officials are aware of the prayer provision and respect the right of players of all faiths to express themselves."

Abdullah, who is Muslim, returned an interception 39 yards for a touchdown in the 41-14 win over the New England Patriots. After the game, Abdullah said he believed he was flagged for sliding on his knees, not for doing a religious prostration.

But Tuesday morning, NFL spokesman Michael Signora said the flag was incorrect. Signora stuck by that statement in an email to USA TODAY Sports on Thursday but added that an official would not be "downgraded" on a close call.

"As part of evaluating the performance of our game officials, the officiating supervisors recognize that for an incorrect call on a close judgment play the official may have used appropriate reasoning. On such a call, the official is not downgraded," he said.

Signora added, "With regard to Husain Abdullah, a player who goes to the ground as part of religious expression should not be penalized. While he did slide immediately before beginning his prayer, this was not a correct call and the play should not have resulted in a penalty."

The NFLRA said the penalty was one of two in the last two weeks the NFL publicly announced were errors, but later the officiating department said the calls were correct.

On Sept. 21, officials flagged a blindside block on Philadelphia Eagles quarterback Nick Foles as a personal foul against the Washington Redskins. Troy Vincent, the NFL executive vice president of football operations, said the hit was legal. But the NFLRA said the officiating department graded the call as correct a day after Vincent's comments.

"In the case of the block on Nick Foles, by rule, it was not a foul because the quarterback was pursuing the play, the contact was not to the head or neck area, and the play was not over," Signora said. " However, the referee – watching the play at full speed and without the benefit of a replay review – judged that the block was late and threw a flag. While not a correct call, we understand why it was made."

NFLRA executive director Jim Quirk said in the statement that "consistency in penalty enforcement is extremely important to the players, coaches and fans. Uncertainty as to what the League wants called is not a road you want to go down."